ESET
discovered two malicious apps capable of using this 2FA bypass on the
Google Play store. A developer named BTCTurk Pro Beta uploaded the first
app — similarly dubbed BTCTurk Pro Beta — on June 7. The second app,
sBtcTurk Pro Beta, arrived on Google Play on June 11 from a developer
named BtSoft. Both of these apps registered around 50 downloads before
the Slovakian security firm reported them to Google’s security team.

Upon installation, the apps request a permission known as
Notification Access. This privilege enables the app to read
notifications from other apps, dismiss them and click on buttons within
those notifications. Notifications include SMS messages containing 2FA
codes.

When granted, the malicious apps direct users to a fake login page
for Turkish cryptocurrency exchange BtcTurk. The apps then display an
error message while they secretly send those login credentials to a
remote server. The individuals behind this campaign use those details as
well as the Notification Access permission to authenticate themselves,
conceal any 2FA prompts and empty their victims’ cryptocurrency
accounts.

The Limitations of SMS-Based 2FA

These malicious apps illustrate the long-running limitations of SMS-based 2FA. In December 2018, for example, ESET
came across an Android Trojan designed to steal funds out of mobile
users’ PayPal accounts, including those protected by 2FA. Earlier that
year, attackers used SMS intercept techniques to bypass 2FA in a
security incident that affected some computer systems of Reddit.

Prepare for the Next Mobile 2FA Bypass Threat

To help defend their organizations against mobile malware that comes with a 2FA bypass, security leaders should invest in a unified endpoint management (UEM) solution that uses compliance rules and detection logic to scan for mobile malware. Companies should also protect corporate-owned mobile devices
by keeping software up to date, implementing password best practices
and writing security policies that limit app installations to official
marketplaces.

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